Title: Identifying insects, clouds, and precipitation using vertically pointing polarimetric radar Doppler velocity spectra

Abstract

This study presents a method to identify and distinguish insects, clouds, and precipitation in 35 GHz (Ka-band) vertically pointing polarimetric radar Doppler velocity power spectra and then produce masks indicating the occurrence of hydrometeors (i.e., clouds or precipitation) and insects at each range gate. The polarimetric radar used in this study transmits a linear polarized wave and receives signals in collinear (CoPol) and cross-linear (XPol) polarized channels. The measured CoPol and XPol Doppler velocity spectra are used to calculate linear depolarization ratio (LDR) spectra. The insect–hydrometeor discrimination method uses CoPol and XPol spectral information in two separate algorithms with their spectral results merged and then filtered into single value products at each range gate. The first algorithm discriminates between insects and clouds in the CoPol Doppler velocity power spectra based on the spectra texture, or spectra roughness, which varies due to the scattering characteristics of insects vs. cloud particles. The second algorithm distinguishes insects from raindrops and ice particles by exploiting the larger Doppler velocity spectra LDR produced by asymmetric insects. Since XPol power return is always less than CoPol power return for the same target (i.e., insect or hydrometeor), fewer insects and hydrometeors are detected in the LDR algorithmmore » than the CoPol algorithm, which drives the need for a CoPol based algorithm. After performing both CoPol and LDR detection algorithms, regions of insect and hydrometeor scattering from both algorithms are combined in the Doppler velocity spectra domain and then filtered to produce a binary hydrometeor mask indicating the occurrence of cloud, raindrops, or ice particles at each range gate. Forty-seven summertime days were processed with the insect–hydrometeor discrimination method using US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program Ka-band zenith pointing radar observations in northern Oklahoma, USA. For these 47 d, over 70 % of the hydrometeor mask column bottoms were within ±100 m of simultaneous ceilometer cloud base heights. All datasets and images are available to the public on the DOE ARM repository.« less

Authors:

Williams, Christopher R. ;

• Search DOE PAGES for author "Williams, Christopher R."
• Search DOE PAGES for ORCID "0000-0001-9394-8850"

Johnson, Karen L.; Giangrande, Scott E. ;

• Search DOE PAGES for author "Giangrande, Scott E."
• Search DOE PAGES for ORCID "0000-0002-8119-8199"

Hardin, Joseph C. ;

• Search DOE PAGES for author "Hardin, Joseph C."
• Search DOE PAGES for ORCID "0000-0002-8489-4763"

Öktem, Ruşen ;

• Search DOE PAGES for author "Öktem, Ruşen"
• Search DOE PAGES for ORCID "0000-0002-6566-7020"

Romps, David M.

Publication Date:

Wed Jun 16 00:00:00 EDT 2021

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center; Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Univ. of Colorado, Boulder, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

Contributing Org.:

Pacific Northwest National Laboratory (PNNL); Brookhaven National Laboratory (BNL); Argonne National Laboratory (ANL)

OSTI Identifier:

1797317

Alternate Identifier(s):

OSTI ID: 1798695; OSTI ID: 1809056; OSTI ID: 1813789; OSTI ID: 1814495; OSTI ID: 1963101

Report Number(s):

BNL-221828-2021-JAAM; PNNL-SA-159907
Journal ID: ISSN 1867-8548

Grant/Contract Number:  

508641; SC0012704; DEAC02-05CH11231; AC02-05CH11231; AC05-76RL01830; SC0021345

Resource Type:

Published Article

Journal Name:

Atmospheric Measurement Techniques (Online)

Additional Journal Information:

Journal Name: Atmospheric Measurement Techniques (Online) Journal Volume: 14 Journal Issue: 6; Journal ID: ISSN 1867-8548

Publisher:

Copernicus GmbH

Country of Publication:

Germany

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; atmospheric science; dual-polarization; radar; weather; insects, cloud radar, Doppler velocity spectra